Free radicals probably aren't a common topic of conversation around the barbecue, but an information evening will shine an ultra violet (UV) light on their impact on the taste of beer tomorrow night.

There's a lot that can wrong when it comes to beer brewing, but many of the problems can be traced back to one thing - free radicals.

They're molecules that have unpaired electrons, and in a relentless search for a pair, they steal electrons from other healthy molecules and damage them in the process.

And in beer, that translates to a stale taste and smell.

"Some of the things that can go wrong with beer are the most interesting," chemist Dr Renee Beale said.

She's one of the organisers behind Radical Beer - an evening of beer tasting with a presentation of the science behind good and bad beer, put on by the ARC Centre of Excellence for Free Radical Chemistry and Biotechnology.

"Some of the things that go wrong with beer can be to do with free radicals, which is what we research.

"I'm fascinated by it because it can also be a fun event but it's an example of how free radicals do something that's quite interesting.

"If it's disgusting it's even more fascinating."

The night will feature a talk by avid home brewer and free radical chemist Dr Philip Barker.

Dr Beale said that when UV light hits the hops in a beer it creates a chain reaction with free radicals, and 'nasty-smelling' molecules are produced in the process.

It's one of the reasons you'll mainly see beer bottled in brown glass, while beer in clear glass bottles has a modified form of hops that doesn't undergo the chemical reaction.

She says beer should be stored out of the sun and in a cool and constant temperature.

"There's a lot of chemical research that goes on in beer brewing and people probably don't realise that," Dr Beale said.

"The big manufacturers have a few chemists on board, and every now and then they have a bad batch, but a lot of research goes into preventing it because they can lose money."

The Radical Beer event at the Five Islands Brewery will provide a free seminar and science experiment (tastings will be charged) and will show examples of how free radicals have affected the taste and smell of a beer.